Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0749 PM CDT Mon Apr 20 2020 Valid 210100Z - 211200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE OZARKS...NORTHEAST TEXAS AND EASTERN WISCONSIN... ...SUMMARY... Marginally severe storms with strong wind gusts and hail will be possible early this evening in the Ozarks. A few storms with hail could also occur late tonight in northeast Texas. ...Ozarks... The latest water vapor imagery shows a subtle shortwave trough moving southeastward through the lower Missouri Valley. Scattered thunderstorms are ongoing ahead of the shortwave trough in a west-northwest to east-southeast corridor of drier mid-level air. The storms are located ahead of a cold front in an airmass that is weakly unstable. Surface dewpoints are only in the 45 to 55 degree F range. This is contributing to weak instability with the RAP showing MLCAPE of 250 to 500 J/kg. In addition, the WSR-88D VWP at Springfield, Missouri has 0-6 km shear near 40 kt. This environment will continue to promote a marginal severe risk for another hour or two early this evening. Hail and strong gusty winds will be the primary threats. ...Eastern Wisconsin... A shortwave trough is evident across the upper Mississippi Valley this evening. At the surface, a cold front associated with the trough is moving southeastward across south-central Wisconsin. Thunderstorms are developing near the front ahead of the shortwave trough along the leading edge of a band of large-scale ascent. Although instability is very weak, wind profiles are unidirectional with 30 to 40 kt of flow just above the surface. This is will create conditions favorable for strong wind gusts with thunderstorms that move eastward toward Lake Michigan this evening. The threat is expected to continue for a couple more hours. ...Northeast Texas... A shortwave ridge will move eastward across the southern Rockies this evening as west-northwest mid-level flow remains over the southern Plains. Low-level moisture advection will continue across the eastern half of Texas. In response, instability should increase with time this evening into the overnight period across parts of east and north Texas along the western edge of a moist airmass. As a low-level jet strengthens across central Texas, thunderstorm development is expected to take place on the northern edge of the stronger low-level flow. These storms should remain elevated and move southeastward along the instability axis across northeast Texas late tonight. MUCAPE of 1000 to 1200 J/kg, effective shear of 50 to 60 kt and steep mid-level lapse rates may be enough for marginal hail threat, mainly in the 09Z to 12Z timeframe. ..Broyles.. 04/21/2020Read more
from SPC Forecast Products http://www.spc.noaa.gov/products/outlook/day1otlk_0100.html
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